Self-tuning control of balloon internal pressure in ileus tube

Seki, Takeshi*; Naganawa, Akihiro*; Oka, Kiyoshi; Yoshino, Junji*

Enteroscopy was usually performed by the double balloon or capsule endoscopes. However, it is difficult to use these endoscopes in patients who suffer from intestinal obstruction and adhesion. We have developed a new endoscope that can be used in patients who suffer from these problems; the instrument consists of an ileus tube and an optical fiberscope (diameter 1.1 mm). The entire small intestine can be observed by controlling the internal pressure of the balloon in the ileus tube and by pulling the tube out at a constant speed. In our previous study, we developed an internal pressure control device that consists of a balloon attached to an ileus tube and a medical syringe. We also verified the control performance of this device. In this study, we have designed a new two-degrees-of-freedom control system having self-tuning capabilities that enhances the control performance for various types of syringes doctors use usually. The effects of the proposed method are illustrated by the experiment. The obtained results show that balloon pressure in the reference response satisfactorily tracks the output of the reference model and can be settled within 2% in steady state. In addition, the disturbance rejection properties of the PID control method were affected by the changes in balloon pressure, but this problem can be solved by using the proposed control system.